Java runs out of memory. Is this not a memory leak?
I don't think you have a leak at all, you are just using the options wrong. With -Xmx2G you are telling Java that it can use up to 2G for the heap. At the same time you are telling Kubernetes that the absolute limit for memory is 2Gi. Now, Java uses memory that is not on the heap, so when it tries to expand the heap to 2G it runs out and the pod is killed.
To fix the problem make sure that you allow a reasonable margin for the memory that is outside the heap. Increase the Kubernetes limit to 3G temporarily and then scale it down when you know how much native memory you need. I would guess that 2.5G is a reasonable level, but that is just a guess. Alternatively you can decrease the Java heap size and run with a 1.5G heap (or less) to leave some room for the native memory.